1. Field of the Invention
Optical image transmitting devices with particular reference to an array of optical elements for effecting image inversion.
2. Discussion of the Prior Art
A need for this invention arises from the fact that the simplest optical systems for photocopying tend to produce reverse, mirror-image, copies rather than true copies of an original (an example is contact printing). There are several conventional methods for correcting this image reversal, all with some disadvantages and limitations. One method, the use of a mirror, is appropriate only when a lens or other imaging element provides sufficient space in the optical path. Another method is the use of two copying steps with temporary storage of the reversed image. Also, in some applications, it is possible to project the light through the transparent or translucent base material of the original or the copy, thus achieving the required reversal. Still another method of correcting mirror imaging is "reversed motion copying", e.g. as in U.S. Pat. No. 3,398,669. In this method, the original is scanned by a narrow aperture and copied in a reversed sequence. The limitation on this method is that the slit aperture must normally be very narrow in order to achieve good image resolution. This implies a slow printing speed in order to achieve adequate exposure.
Fiber optic bundles are particularly appropriate for transporting slit images and facilitating the output of light onto opaque originals but conventional fibers do not correct the inherent limitations of reversed motion copying.
A principal object of this invention is to provide one-way image reversal which is appropriate to improved efficiency in photocopying.
Another object is to provide an image-reversing array of optical elements which may be used in place of or in conjunction with conventional fiber optic arrays in photocopying systems.
Still another object is to provide in photocopying systems, slit image inversion in the direction of slit travel permitting the use of unusually wide object scanning slits and high printing speeds without loss of resolution.
Other objects and advantages of the invention will become apparent from the following description.